In typical ball screw devices, a recirculation tube is used to circulate the bearings from the bottom of the ball screw back to the top. Typically a recirculation tube is positioned outward from the body of the nut and as such the bearings in the recirculation tube each have greater radii relative to the radii of those in the tracks between the threaded shaft and the threaded nut. It is known that centripetal force on the bearings is determined by the speed of rotation and the bearing's distance from the rotational axis. Accordingly, the bearings in the recirculation tube experience greater centripetal force during rotation of the ball screw than the other bearings. If the rotation is at a high enough speed, the centripetal force can impede free motion of bearings in the recirculation tube with detrimental effect on ball screw performance and durability. As such, typical ball screws are not conducive for use in an environment where the entire ball-screw assembly will rotate at high speed.
Additionally, the ball recirculation tube requires additional packaging space, which may not be suitable for some environments.
New ball screws are needed to address these concerns.